The invention relates to a method for the preparation of a silicone defoamer composition. To a substantial degree, the foaming of liquids is a serious problem in various industrial methods as generally encompassed by those treatment processes which use a liquid as the treatment agent and those processes in which a liquid is itself subjected to treatment. Foaming of the liquid may reduce the efficiency of an essential treatment process, and product quality may also be compromised.
As is known, the problem of foaming may be addressed by the application of a defoamer having a foam-breaking effect, which serves to extinguish the foam, and/or having a foam-inhibiting effect, which serves to prevent or reduce the foaming tendencies of the liquid. In particular, silicone defoamers are preferred because they are chemically stable, rarely adversely affect the object of application, and have a relatively high defoaming activity even at very low doses.
Various silicone defoamers have been proposed in the art. For example, Japanese Patent Publication Number 45-23613 (23,613/70) describes a defoamer composed of dimethylpolysiloxane oil, a particular siloxane resin, and silica aerogel. Japanese Patent Publication Number 47-1602 (1,602/72) describes a defoamer produced by heating polyorganosiloxane with a finely divided additive such as silica, etc., in the presence of alkali.
However, problems are encountered with the defoaming activity of the prior silicone defoamers described above, particularly due to the brief duration of their foam-inhibiting effect. As a consequence, the requirements of any process which requires long-term foam suppression cannot be met in an entirely satisfactory manner.